A unique family of alpha-D-galactopyranosyl-containing glycoprotains has been isolated from a membrane fraction of Ehrlich ascites tumor cells. This research project has as one of its central aims the complete characterization of these glycoproteins. We shall employ chemical procedures (methylation and Smith degradation studies), enzymatic degradation with specific glycosidases (alpha- and beta-galactosidases, alpha- and beta-hexosaminidases, and alpha- and beta-mannosidases) and lectin binding studies in order to sequence the carbohydrate moiety. The alpha-D-galactosyl-containing glycoproteins from TA3-Ha and TA3-St murine carcinoma cell plasma membranes will also be isolated. We shall determine the structural relationships, if any, of these glycoproteins to each other and to the Ehrlich cell glycoproteins. Chemical and immunochemical techniques will be employed.